Meloidogyne enterolobii is a soil-borne disease that seriously harms crop production in tropical areas, and the agricultural losses caused by it are incalculable every year. For the control of root-knot nematodes, the traditional physical and chemical control methods have some disadvantages, while biological control is environmentally friendly and safe for people and livestock, so it has gradually become a research hotspot. This study used the impregnation method to screen strains with killing activity against the second instar larvae of M. enterolobii. The fermentation conditions and treatment time of the screened highly active strains were optimized. The strains were identified using 16S rRNA sequencing as well as physiological and biochemical methods, and growth promoting characteristics were analyzed. The research results indicated that the nematicidal activity of the fermentation supernatant of BWLY1PSB-1, BWLY2X-4 and BWLY3X-11 were more than 65%. Through morphological, physiological and biochemical characteristics, and molecular biology identification, BWLY1PSB-1, BWLY2X-4 and BWLY3X-11 were identified as Staphylococcus pateuri, Bacillus methylotrophicus and Bacillus sp., respectively; The nematicidal activity of the fermentation supernatant of each strain could reach the maximum after 24 h treatment of nematodes, and the optimal fermentation medium was LB medium, and the nematicidal activity of the supernatant reached relatively high when cultured for five days. The research results on the growth promoting characteristics of thee strains indicated that BWLY1PSB-1 had the ability to produce iron carriers and IAA, while BWLY2X-4 and BWLY3X-11 had the ability to produce proteases, cellulases, iron carriers, and IAA. The preliminary screening of excellent strains that can effectively control plant root-knot nematodes and have rowth promoting characteristics would enrich the microbial resources for the biological control of plant root-knot nematodes.

Hyper-spectral remote sensing technology was used to explore the estimation method of nitrogen content in the leaves of macadamia to achieve a rapid diagnosis of nitrogen nutrition in macadamia trees. Lincang and Xishuangbanna were chosen as the research area to obtain the spectral reflectance and nitrogen content of the leaves of macadamia varieties O.C and HAES344. Firstly, multiple mathematical transformations were performed on the original spectral reflectance using logarithmic transformation, derivative transformation, and their combinations. Then, the correlation between nitrogen content of macadamia leaves and spectral data of different transformation forms was analyzed. Under the principle of larger determination coefficient, the wavelength corresponding to the peak characteristic point in the determination coefficient curve was selected as the nitrogen sensitive wavelength, thus the corresponding spectral variables of nitrogen sensitivity were obtained. Stepwise regression was used to further optimize the nitrogen sensitive spectral variables, and the methods of multiple linear regression (MLR), partial least squares regression (PLSR), and support vector regression (SVR) were used to construct the nitrogen content estimation models for macadamia leaves. Finally, the performance of the models was tested using validation and test sets, respectively. The results showed that the MLR, PLSR and SVR models all performed well in estimation, and the ratio of performance to standard deviate (RPD) of both the validation and test sets were above 2.0. Among them, the PLSR was the optimal estimation model, its RPD of the validation set and the test set was 2.099 and 2.110, respectively. The 19 nitrogen sensitive spectral variables selected from 6 types of transformation spectral data, including reflectance (R), logarithmic transformation of reflectance (LR), first derivative of reflectance (FDR), first derivative of logarithmic transformation of reflectance (FDLR), second derivative of reflectance (SDR), and second derivative of logarithmic transformation of reflectance (SDLR) had strong stability in nitrogen spectral response. Based on the selected 19 nitrogen sensitive spectral variables, the conventional regression modeling methods could achieve good estimation results and had strong regional universality. In this study, nitrogen sensitive spectral variables were selected from a variety of transform spectral data, which provided a new idea for the nitrogen content estimation of macadamia leaves.

Coconut meat is the main raw material for coconut products processing, which is mainly obtained by importing dehusked coconut fruits in containers, and the rate of bad fruit is high in the process of transportation and storage. In order to explore the method of rapid differentiation and identification, this study used gas chromatography-ion mobility spectrometry (GC-IMS) combined with principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) to analyze the volatile compounds in coconut meat of unstored normal dehusked fresh coconut fruits (FCM) and deteriorated dehusked coconut fruits under 25 ℃/70%, 35 ℃/80% and 45 ℃/90% (DCM-25, DCM-35 and DCM-45). The results showed that 42 volatile compounds were identified in the four coconut meat, including thirteen alcohols, five acids, eight ketones, ten esters, four aldehydes, two pyrazines and three unknown compounds. The alcohols were the most (including ethanol, butanol and propanol, etc.), followed by acids (including acetic acid and 2-methylpropionic acid, etc.), ketones (including acetone, 3-hydroxy-2-butanone and cyclopentanone, etc.), esters (including butyl caproate, ethyl acetate, butyl butyrate and ethyl butyrate, etc.), aldehydes (including 3-methylbutyraldehyde, pentalaldehyde and heptyl aldehyde, etc.) and pyrazines (2-ethyl-3-methylpyrazine). After deterioration, alcohol, acid and ketone volatile compounds increased. Thirteen characteristic volatile compounds, including 3-methylbutyral, cyclopentanone, 3-methylbutanol monomer, butanol monomer, heptaldehyde, acetone, 2-methylpropanol monomer, 2-heptanone monomer, heptanic acid, butyl butyrate monomer, ethyl acetate, ethanol dimer and 2-ethyl-3-methylpyrazine monomer, were analyzed by OPLS-DA, with variable importance in projection greater than 1. The characteristic volatile compounds in FCM were cyclopentanone and butanol monomer by differential heat map. The characteristic volatile compounds in DCM-25 were 2-heptanone monomer, butyl butyrate monomer, ethyl acetate, ethanol dimer and 2-ethyl-3-methylpyrazine monomer (mainly esters, alcohols and ketones). The characteristic volatile compounds in DCM-35 was heptanoic acid (mainly acids). The characteristic volatile compounds in DCM-45 were 3-methylbutyraldehyde, heptyl aldehyde and acetone (mainly aldehydes and ketones). This study would provide theoretical basis for the screening of deteriorated dehusked coconut fruits.

Calix[4]arene, a class of host compounds, is capable of forming host-guest compounds with guest molecules through hydrogen bonding, electrostatic forces, or van der Waals forces. With the incorporation of sulfur atoms into the molecular structure of calix[4]arene, the cavity size of calix[4]arene would increase. At the same time, sulfur atoms offer strong coordination abilities to trace amounts of variable metallic ions (Mn²⁺, Cu²⁺) presented in natural rubber. The complexes prepared by sulfothiacalix[4]arene salt and metal ions can mitigate catalytic effects of variable metallic ions on the aging reactions of natural rubber, thus improving the thermal oxidative aging performance of natural rubber. Sulfothiacalix[4]arene was synthesized and the protective effect of sulfothiacalix[4]arene on the thermo-oxidative aging behavior of natural rubber was investigated by means of FTIR, DSC, TGA and so on. After the experiment, compared with the samples without the addition of sulfothiacalix[4]arene, it was found that the signals of O-H, C=O and C=C in the FTIR spectra of the samples with the addition group were weakened, the thermo-oxidative aging temperatures on the DSC curve were increased by about 18.87 ℃ and 29.90 ℃, and the epitaxial initial thermal decomposition temperatures in TGA were increased by 11.82 ℃ and 15.03 ℃, respectively. It is concluded that sulfothiacalix[4]arene could be used as a highly effective anti-aging agent in the thermo-oxidative aging of natural rubber.

A new cassava variety Gui 1289 with excellent comprehensive traits such as good plant type, high yield, high starch, and wide adaptability was bred by systematic breeding procedures using SC5 as the maternal parent and SC205 as the paternal parent. The average yield of fresh roots for this variety was 49.92 t/hm² in regional test over the years, which was 24.21% higher than that of the control NZ 199. The average yield of fresh roots was 50.76 t/hm² in production test, which was 21.26% higher than that of NZ 199. The average starch content in regional test over the years was 30.22 g/100 g, an increase of 5.42 g/100 g compared to NZ 199. The average starch content in production test over the years was 29.96 g/100 g, an increase of 5.57 g/100 g compared to NZ 199. The field test of Tetranychus cinnabarinus showed moderate resistance. It is suitable for popularization in cassava planting areas such as Guangxi, Guangdong, Hainan and Jiangxi, and so on. This study would provide a new germplasm resource for achieving high-quality production of cassava in China, which is of great significance to increase the income of the farmers and increase the efficiency of enterprises

The 16S rRNA high-throughput sequencing analysis was conducted on the rhizosphere soil of Cassava South China No.12 under treatment without fertilization (CK), organic fertilizer (T₁), conventional fertilization applied with organic fertilizer (T₂), and reduced chemical fertilizer applied with organic fertilizer (T₃) by using the Illumina Nova 6000 sequencing platform to study the effects of chemical fertilizer application combined with organic fertilizer on the growth of cassava and the bacterial diversity and community structure in cassava rhizospheric soil. T₃ not only significantly increased the height and stem thickness of cassava, but also improved the yield of cassava, compared to CK. Cluster analysis was performed on the sequences based on 97% similarity, the OTUs numbers of CK, T₁, T₂ and T₃ are 3603, 1688, 1276 and 3317 respectively. Different fertilization methods altered the diversity and richness of soil bacteria, with the species diversity ranked from highest to lowest as CK>T₃>T₁>T₂. Based on PCoA and cluster analysis, the community composition of CK and T₃ was similar, the community composition of T₁ and T₂ was similar. The dominant phylum in cassava rhizospheric soil under different fertilization treatments were Proteobacteria, Bacteroidetes, Acidobacteria, Firmicutes, Actinobacteria and Chloroflexi. The relative abundance of Proteobacteria, Bacteroidetes and Actinobacteria increased under T₃ treatment, while the relative abundance of Firmicutes and Chloroflexi decreased. Redundancy analysis results indicated that available potassium was the main factor affecting the bacterial community in the cassava rhizosphere soil. In summary, the study demonstrates that reduced chemical fertilizer application combined with organic fertilizer not only increases the yield of cassava, but also changes the community structure and diversity of the bacterial in the rhizosphere soil. The results would provide a solid theoretical foundation for the development of a green, efficient, and sustainable cassava industry.

In order to clarify the situation of macrofungal resources in Haikou, the analysis on species diversity of macrofungi in Haikou was carried out based on the samples collected by the authors in 2022 and deposited in Fungarium of the Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (FCATAS). A total of 110 species of macrofungi, belonging to 69 genera, 32 families, 10 orders, and 2 phyla, were identified based on morphological and molecular evindence. Two new species, 10 new Chinese records, and 33 new records in Hainan were found. Five dominances with more than 5% in total species were Polyporaceae, Hypoxylaceae, Agaricaceae, Xylariaceae, Omphalotaceae and Pleurotaceae, including 55 species, accounting for 50.00% of the total species. The assessment of the utilization value of the macrofungi showed that there were 8 edible species, 14 medicinal species, and 3 poisonous species in Haikou, indicating the resources have good application prospects. According to the records of “Redilist of China’s Biodiversity-Macrofungi”, 44 species of macrofungi in Haikou were assessed. Among them, Macrocybe gigantea was near to be threatened (NT), 27 species were least concerned (LC), and 16 species were data deficient (DD). The present study would provide important scientific basis for the protection, utilization and management of macrofungal resources in this area.

Powdery mildew (Erysiphe quercicola) can infect a variety of economically important crops, and seriously threatens the rubber industry. In order to explore the molecular mechanism of the pathogenesis, the genome of E. quercicola (HO-73 strain) was sequenced and 133 candidate secreted effector proteins (candiate secreted effector proteins, CSEPs), which have homologous proteins only in other powdery mildew, were identified. An effector protein, CSEP02974, which is conserved in powdery mildew, was identified. The function of the signal peptide in secreted protein was assayed using the yeast secretion system. CSEP02974 was a cytoplasmic effector protein verified by using the Agrobacterium-mediated transient expression system and localization analysis. Further, CSEP02974 expression in Arabidopsis thaliana inhibited chitin- or flg22-induced callose deposition and ROS accumulation. The result suggests that CSEP02974 is a virulence factor in suppressing plant immunity. CSEP02974 was silenced by spraying exogenous double-stranded RNA on E. quercicola. Pathogenicity analysis showed that this gene silencing led to inhibitions of extended growth and infection. In conclusion, this study identified a key E quercicola virulence factor, which would provide an important clue on the mechanism of interaction between rubber tree and E. quercicola.

Tonoplast intrinsic proteins (TIPs), which comprise a subfamily of aquaporin (AQP) mediating the water balance within plant cells, could be divided into five phylogenetic groups on the basis of sequence similarity, i.e., TIP1–TIP5. Based on the full-length transcriptome previously described in tigernut (Cyperus esculentus), a tuber-abundant TIP gene named CeTIP4;1 was cloned and characterized in this study. Sequence analyses revealed that CeTIP4;1 contained two conservative introns with a complete coding sequence of 753 base pairs (bp), putatively encoding 250 amino acids with the theoretical molecular weight of 25.57 kDa, the isoelectric point (pI) value of 6.02, and the grand average of hydropathicity (GRAVY) value of 0.884, implying its acidic and hydrophobic features. The deduced peptide possessed one conservative major intrinsic protein (MIP) domain and exhibited similar structural features with the structure resolved AtTIP2;1. Classification of CeTIP4;1 into the TIP4 group was supported by the phylogenetic analysis, which showed that CeTIP4;1 clusters with AtTIP4;1, OsTIP4;1, OsTIP4;2 and OsTIP4;3 with sequence similarities of 69.62%–82.94%. After gene cloning, a plant expression vector for subcellular localization, i.e., pNC-Cam1304-CeTIP4;1, was successfully constructed. When transiently overexpressed in tobacco (Nicotiana benthamiana) leaves, confocal laser scanning microscopy imaging showed that CeTIP4;1 was unexpectedly localized to the cell membrane. Further expression analysis indicated that CeTIP4;1 exhibited an apparent tissue-specific expression patter, predominately expressed in tuber, root, rhizome, and shoot apex. Moreover, among the four typical stages of developmental tuber examined in this study, i.e., initiation, medium swelling, late swelling, and maturation, CeTIP4;1 exhibited a bell-like expression pattern, peaking in medium swelling tubers and lowest in maturation tubers. These results lay a solid foundation for further uncovering the mechanism of water balance in tigernut tubers.

Pitaya contains abundant nutrients and is highly preferred by consumers. However, this fruit is prone to quality deterioration problems such as yellowing of fruit scales, fruit dehydration, peel shrinkage and decay during the postharvest storage period, which seriously affect its commercial value. Jindu No.1 variety was used to investigate the effect of gibberellin composite chitosan treatment on the postharvest quality and antioxidant capacity of pitaya. Pitayas of uniform size, consistent maturity and intact condition were randomly selected for six types of treatments: water (control group), 5 g/L chitosan, 50 mg/L gibberellin, 25 mg/L gibberellin + 5 g/L chitosan, 50 mg/L gibberellin + 5 g/L chitosan, and 100 mg/L gibberellin + 5 g/L chitosan treatments. The pitayas were stored at a constant temperature of 25 ℃ after treatment, and postharvest quality indicators including lipoxygenase activity (LOX), malondialdehyde (MDA) content, antioxidant substance content and antioxidant enzyme activity were measured regularly. The results showed the well-maintained storage quality of pitayas treated with 50 mg/L gibberellin + 5 g/L chitosan. After 12 days of storage, the rate of fruit scale yellowing and water loss was reduced by 15.91% and 20.75% respectively compared with those of the control. The soluble sugar content, color a^* value and L^* value of the fruit were substantially higher than those of the other groups and the soluble pectin content was considerably lower than those in the other groups. The 50 mg/L gibberellin + 5 g/L chitosan treatment could also maintain the improved antioxidant capacity of pitaya. After 12 days of storage, MDA content and LOX activity in the fruit decreased by 16.04% and 19.23% respectively compared with the control. The content of antioxidant substances such as flavonoids, total phenols, reduced glutathione (GSH) and reduced ascorbic acid (AsA) increased by 10.07%, 10.00%, 31.43% and 12.93%, respectively. The activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased by 17.61%, 79.22% and 15.00% respectively compared with those of the control. The gibberellin composite chitosan treatment with appropriate concentrations could effectively maintain the postharvest quality of pitaya, increase the fruit’s antioxidant capacity, reduce membrane damage caused by lipid peroxidation, delay the ripening and aging of pitaya, and extend the preservation period. In addition, composite treatments could be considered a green, environmentally friendly, economical and effective preservation method that can serve as an application reference for pitaya storage, transportation and preservation industry after harvest.